The main objective of this project is to characterize immunological mechanisms in the Syrian hamster and mink, with particular attention to the role played by various Ig classes. Experiments in the hamster utilizing viable organisms (rickettsia, rabies virus) indicate that the antibody response involves a different 7S Ig class than found with nonadjuvantized protein antigens. Lymphomas arising in hamsters, either spontaneously or subsequent to SV-40 inoculation, are being characterized and utilized as sources of monoclonial Ig and cell-class specific antigens. Immunological studies in mink mainly involve elucidating the pathogenesis of Aleutian disease. This immune complex disease in mink appears to primarily involve the deposition of IgA in glomeruli and current ongoing projects are designed to quantify the actual Ig class of anti-Aleutian disease virus and the composition of the circulating complex.